1. Field of the Invention
The present invention relates to an encryption method, a communication system, a transmission device, and a data input device.
2. Description of the Related Art
More and more communication has become wireless between a computer and its peripheral devices such as a keyboard and a mouse. Such communication is conducted by infrared or at high radio frequencies. Unlike wire communication, however, information is subject to intercept in wireless communication. Therefore, the contents of communication are concealed.
Japanese Laid-Open Patent Application No. 9-190264, for instance, discloses a wireless data input system. According to this system, the contents of communication are concealed by encoding keyed-in data based on a security code.
According to this system, however, the data is single-encoded with a fixed ID, so that the data may be decoded with relative ease by processing the data rows.